Peelable release foils are widely used as removable protection foils for adhesive tapes, self-adhesive labels, or adhesive sanitary and hygiene products, in order to prevent adhesion of these single- or double-side-adhesive products during storage or processing. They have to feature good release effect with respect to adhesives such as pressure-sensitive adhesives or other adhesive materials.
Siliconized release foils are already known from the prior art, for example from EP 1 277 802 A1 or EP 0 769 540 A2.
Siliconized release foils are usually produced by providing single- or multilayer foils with a polysiloxane coating. These foils are first coated with a polysiloxane that has not yet been hardened, and once the coating process has taken place the polysiloxane is then preferably thermally hardened.
However, a disadvantage of a process of this type is that the plastics foils requiring coating have to meet certain minimum mechanical and/or thermomechanical requirements, in order that they withstand the thermal stresses during the curing procedure for the polysiloxane coating. Accordingly, the plastics foils have to have a certain minimum thickness, dependent on the polymer material from which they have been produced, in order that the coating procedure and in particular the curing procedure do not cause any thermal or thermomechanical overloading of the foil to be coated or of the coated foil, with consequent undesired adverse effects on quality or on processes, like for example formation of folds, web shrinkage, web break-offs, or defects in the polysiloxane coating.
However, costs are not the only reason for the provision of a comparatively low thickness of a siliconized release foil for many applications.
There is therefore a need to provide processes which can provide single- or multilayer plastics foils with a curable polysiloxane coating which do not show the above-mentioned disadvantages.
It was therefore an object of the present invention to provide a process for producing a single- or multilayer plastics foil provided with a thermally cured polysiloxane coating on one side, by neither having to use a foil meeting certain minimum mechanical requirements, in particular a certain minimum thickness for the application of the polysiloxane coating, nor having to postpone the reduction of the single- or multilayer plastics foil to a desired thickness until after the application of the polysiloxane coating.